In this case, the intuition is that bottled water uses more energy—and thus releases more greenhouse gases—than plain old tap water. The point is really obvious: just think about the energy that’s required to manufacture bottles, and you can pretty easily guess that bottled water will be more energy-intensive than water from the tap. In fact, it’s so obvious, it almost seems pointless to do a study

But it turns out that there’s a very interesting point to be made: the gap between bottled water and tap water is simply enormous. Based on European data used in the Swiss study, water straight from the tap has about one half of one percent of the climate-warming impact of the most benign bottled water—and less than a thousandth of the overall environmental impact of the most energy-intensive bottled water.

In the chart to the left, I’m deliberately leaving the numbers vague. The two bars actually average of a number of different figures—different drinking water systems, bottling options, and water temperatures. So the numbers are a bit meaningless. Still, they give a sense of the magnitude of the difference between bottled water and tap water.

In this case, the most important message isn’t simply that tap water is better—it’s the raw scale of the gap between tap water and bottled water. Of course, bottled water doesn’t rank particularly high on the list of climate offenders, compared to cars and trucks, coal fired power plants, and the like. Still, if you’re a bottled-water drinker, and you’re looking for a quick and easy way to reduce your carbon footprint—and you’re lucky enough to live in a place with clean, tasty tap water—playing taps (ha!) for your bottled water is a pretty good place to start.

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Comments

Don

July 22, 2008 at 5:07 am

Dear Steve: And on top of it, the Swiss study does not consider transport costs across the Atlantic. Consider French water of a certain variety, bottled in heavy glass, flown from Paris! What about a new product that could have huge appeal owing to its purity, Antarctic glacial water! Martian water could be next; it’s there, science tells us.

Thinking about the climate impact of manufacturing and transporting beverages in general…How about a graph showing the gap between imported vs. local beer? I mean, I like Heineken, but I just can’t bring myself to buy a 12 pack that has traveled from the Netherlands. I’ve also been wondering what the average travel distance is for a bottle of soda?

I just ran across this great article on the carbon footprint of orange juice. Pepsi commissioned a study of their Tropicana brand orange juice, and found out that:* A half gallon container of orange juice emits 3.75 pounds of CO2.* Most of this carbon comes from fertilizer used for the orange trees, not in transportation.* This fertilizer is made from natural gas.If you plot this on your graph above you’d see the US-grown orange juice at 900 kg/1000 liters. Of course comparing orange juice to water isn’t fair, but it goes to show how directly our food derives from fossil fuels.

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